Spell system has been broken since before 3.0, 3.5 made a half-hearted attempt to fix it. However, as written when compared to the rules out of UM, thus by their own rules... Heal is level 20, has the power of 2 3rd level spells (and more) one 4th and does more healing than a maximized cure Crit, thus 7th. It is ridiculous.
Magic Missile is likewise broken compared to their own system, unerring strike on multiple opponents, the very first Magic Missile did a d6 and required a roll.
I have been slowly changing things up and rewriting things for a while, going to roll that out to my players on the next campaign.
I would love a clear separation of divine vs arcane on some system ever. If you require a third party for your power, you are divine caster and since the gods hold the keys to healing (positive and negative energy) that means Bards are divine casters, which actually works better historically for me anyway if you look at Greek and Roman Myth with Apollo and the Muses etc... also by the very description of the Witch she is divine in casting as well.
Divination by definition means that Arcane casters don't get them... that being said some of the powers that are described as divinations can easily be rewritten under other schools, like arcane eye. Things that would absolutely require a 3rd party like true strike would be under divine lists.
Druids are a culture not a class...
Hate Animal Companions, your class/power should not be defined by a creature controlled by the GM.
Rogues getting spells? Made me gag a bit... martial classes don't get magic short of items.
True Resurrection has been completely removed from my games because once you get to that point you have no consequence of death... If there is no consequence there is no drive to avoid it. (yes I know there are "worse things" but still ridiculous).